1. Field of the Invention
The present invention relates to the field of displaying technology, and in particular to a method for manufacturing an OLED device and an OLED device manufactured therewith.
2. The Related Arts
An OLED (Organic Light-Emitting Diode) is a flat panel displaying technique of extremely prosperous future and it shows excellent displaying performance and also possesses various advantages, such as being self-luminous, simple structure, being ultra-thin, fast response, wide view angle, low power consumption, and being capable of achieving flexible displaying and is thus regarded as a “dream display”. In addition, the investment of manufacturing installation is far less than that of liquid crystal displays so that it has attracted the attention of major display manufacturers and becomes the mainstream of the third-generation display devices of the field of displaying technology.
Semiconductor nanocrystals (NCs) are semiconductor nanocrystals having a size of 1-100 nm. Since the semiconductor nanocrystals has a size smaller than exciton Bohn radii of other materials, show a strong quantum confinement effect, and exhibit new material properties, they are also referred to as quantum dots (QDs).
Being excited by external energies (such as photoluminescence, electroluminescence, and cathodoluminescence), an electron leaps from the ground state to an excited state. Electrons and holes, when staying in the excited state, may form excitons. The electrons and the holes recombine and eventually relax back to the ground state. Excessive energy may be released through the process of recombination and relaxation and there could be radiative recombination that gives off photons.
Quantum dots light-emitting diodes (QD-LEDs) have very important value for commercial applications and have attracted strong intentions for research and development for the recent decade. In fact, compared to organic light-emitting diodes (OLEDs), QD-LEDs have various advantages. (1) The light emitting from quantum dot has a line width between 20-30 nm and compared to that of the light emitting from OELDs that is greater than 50 nm, FWHM (Full Width as Half Maximum) is relatively narrow, providing a key factor for achieving color purity of an image. (2) Inorganic materials have better thermal stability than organic materials. When a device is in a condition of high brightness or high current density, Joule heat is a major cause for deterioration of the device. Due to the excellent thermal stability, an inorganic material based device would show an extended lifespan. (3) The organic materials used for the three primary colors of red, green, and blue are of different lifespan and the color displayed by OLEDs would vary with time. However, QDs can be formed of the same material to show different sizes and emission of light with different colors can be achieved through the quantum confinement effect. The same material exhibits the same deterioration rate. (4) QD-LEDs can achieve emission of infrared light, while the wavelength of the emitting light of organic material is generally less than 1 micrometer. (5) Quantum dots are not subjected to constraint imposed by spin statistics and the external quantum efficiency (EQE) may possibly reach 100%.
On the other hand, the evaporation process of OLED devices requires the use of a fine metal mask (FFM). The process is expensive and has a low utilization rate of material and poor yield rate. Thus, it is desired to have a novel OLED device that has a simple manufacturing process, a high utilization rate of material, and a good yield rate.